Hello, I have one question. Can settings in Pre-Processing affect variables able to calculate in Post-Processing?? I have similar cases but in one I can't calculate circumferential velocity. Can anybody help me please??

There is a different in post if you open *.res or *.bak files. In case of a bak-file there might be some variables missing if you didn't choose a full backup in pre.
But if you have a *.res file it is as Glenn explained, the variables in post depend on the models you have chosen in pre (as laminar or turbulent for example).

If you want circumferential velocity specifically you can use turbo mode in cfx post and define your rotation axis then you select calculate velocity components. now you can see circumferential velocity variable in selection list.